# Linked Questions

1answer
3k views

### Disk spinning at the speed of light [duplicate]

Of course, I mean that the edge of the disk is traveling at the speed of light. This is a question that popped into my head a few years ago when I was learning about some basic relativity in high ...
1answer
517 views

### Paradox of the Relativistic Record Player [duplicate]

Possible Duplicate: Invariant spacetime - distance - Circular Motion This is a question that I thought up a few years ago when I was taking mechanics. I asked the professor but didn't really get ...
0answers
86 views

### A question about the relativity of time [duplicate]

Possible Duplicate: Invariant spacetime - distance - Circular Motion I understand that the closer something travels to the speed of light, that time will stretch by a factor, and distance will ...
5answers
1k views

### Euclidean geometry in non-inertial frame

Refer, "The classical theory of Fields" by Landau&Lifshitz (Chap 3). Consider a disk of radius R, then circumference is $2 \pi R$. Now, make this disk rotate at velocity of the order of c(speed of ...
3answers
756 views

### Circumference of a circle in a co-rotating frame of reference

According to Einstein it should be greater than $2 \pi R$ for a co-rotating observer, i.e. $L' = \gamma L$ where $L = 2 \pi R$ in a non-rotating frame and $\gamma$ is the usual Lorentz factor, which ...
3answers
2k views

### Can rotating disk clocked at its center at the speed of light have an outer edge that travels faster than the speed of light? [duplicate]

I have been running this through my head for a few days and I understand I am probably missing something very simple here. If a wheel is spinning the outer edge will travel at a speed that is greater ...
1answer
924 views

### Understanding the “$\pi$” of a rotating disk

Let us say you are in an inertial reference frame with a circular planar disk. If you take your meter measuring rods (or perhaps tape measure) you can find the diameter and circumference of the disk. ...
3answers
744 views

### Speed greater than light in circular motion [duplicate]

We know that linear speed of object going around a circle is $\omega * r$ Now let us take an elastic string and rotate a body of negligible mass with $\omega = 500 rad/s$ It is possible to further ...
0answers
672 views

### The relativistic effects of angular velocity

Imagine I have a circular disk in a vacuum. I apply a constant force, so a constant torque on the disk. My first question is: does this disk have a angular velocity speed limit? I believe it does, ...
1answer
221 views

### How would be tv reception in a spaceship travelling close to speed of light?

My little brother has made me a tough question (specially for a computer science engineer). Imagine that there is a spaceship orbiting earth close at nearly speed of light (say 99%). Someone in earth ...
1answer
220 views

### How does Lorentz Contraction apply to the edge of a spinning disk and is π still constant?

This may seem like a dumb question, as I'm not really a physicist, but here it goes. So, π is the number of diameter distances required to equal the circumference of a 2D disk. Relativity tells us ...
0answers
203 views

### What is the relativistic mass of this spinning ball? [closed]

Relativistic Mass is: $$m_r = \frac{m}{\sqrt{1 - v^2/c^2}}$$ So Einstein says that the faster an object moves, the more mass it gains (relativistic mass). So suppose you have a spherical ball ...
1answer
156 views

### What happens to a ball spinning with peripheral speed near to the speed of light?

I can't imagine such phenomenon. Would it becomes an ellipsoid, or maybe a straight line?
1answer
116 views

### Does the center of a star age faster than its relativistic equatorial surface? If so, how does it maintain its speed and spherical shape?

Imagine a massive (the diameter is millions of miles across) star rotating on its axis at relativistic speeds. Assume, now, that the center of the star is stationary. Note that the center of the star ...
0answers
114 views

### Confusion in Special Relativity: Rotating frame of reference

Suppose we are observing a rotating frame from an inertial frame, free from gravity, and try to measure the circumference of a circle drawn in the rotating frame. Since our measuring rod would be ...

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